A Compact Reconfigurable Antenna for Borehole Radar

A borehole radar (BHR) is a kind of ground penetrating radar that runs in a borehole for subsurface investigations. Considering the limited borehole size and the need for three-dimensional positioning of the unknown targets, BHR antennas are generally required to be both compact and directional. In this paper, a compact reconfigurable antenna is proposed, which can be potentially used for a directional BHR. This antenna contains four dipoles and a certain number of cross-shaped structures. Some PIN diodes are used to control the on-off between the dipoles and the cross-shaped structures for reconfiguring the radiation pattern of the antenna. The simulation results show that the proposed antenna can achieve a wide bandwidth of 52% from 129 MHz to 220 MHz and high directional radiation.